This invention relates to a valve of the type in which a valve member is selectively rotatable within a housing between an open position permitting fluid to flow from an inlet port to an outlet port and a closed position cutting off such flow. The valve of the present invention is particularly adapted to control the flow of hot coolant to the core of the heater of a truck or other vehicle having a water cooled engine.
A coolant often contains rust, dirt or other foreign particles. Such particles tend to become trapped between the housing and the valve member of the valve and, when the valve member is rotated, the particles tend to slide along and score the mating sealing surfaces of a conventional valve. Scoring ultimately causes leakage and requires replacement of the valve.